React Js API 调用 Jest 测试用例？

Posted 2023-02-21

【中文标题】React Js API 调用 Jest 测试用例？

【英文标题】：React Js API call Jest Test Case?

【发布时间】：2021-10-16 15:52:48

【问题描述】：

我正在尝试为我的API调用函数编写测试用例，我不知道我无法成功运行测试的错误在哪里是API调用函数代码和测试用例代码。

export async function getUserTest() 
    fetch(config.apiUrl.myFleetAPI, 
        method: 'GET',
        headers: 
            Accept: 'application/json',
            'Content-Type': 'application/json',
            Authorization: 'Bearer ' + 'GcGs5OF5TQ50sbjXRXDDtG8APTSa0s'
        
    )
        .then((response) => 
            return response.json();
        )
        .catch((reject) => console.log(reject));
    

测试用例代码。

从“反应”导入反应； 从 '../Service/Dashboard/Dashboard' 导入 getUserTest ;

global.fetch = jest.fn();
const mockAPICall = (option, data) => global.fetch.mockImplementation(() => Promise[option](data));

describe('Car Components component', () => 
    describe('when rendered', () => 
        it('should call a fetchData function', async () => 
            const testData =  current_user: 'Rahul Raj', name: 'Lafarge' ;

            mockAPICall('resolve', testData);
            return getUserTest().then((data) => 
                expect(data).toEqual(testData);
            );
        );
    );
);

这是我在尝试运行测试用例时遇到的错误。

 Car Components component
    when rendered
      ✕ should call a fetchData function (5 ms)

  ● Car Components component › when rendered › should call a fetchData function

    expect(received).toEqual(expected) // deep equality

    Expected: "current_user": "Rahul Raj", "name": "Lafarge"
    Received: undefined

      65 |             mockAPICall('resolve', testData);
      66 |             return getUserTest().then((data) => 
    > 67 |                 expect(data).toEqual(testData);
         |                              ^
      68 |             );
      69 |         );
      70 |     );

      at src/Test/MainScreen.test.js:67:30

  console.log
    TypeError: response.json is not a function
        at /Users/rahulraj/Documents/Workproject/Vivafront/lafargeClone/src/Service/Dashboard/Dashboard.js:44:29
        at processTicksAndRejections (internal/process/task_queues.js:93:5)

【参考方案1】：

你的代码有两个问题：

fetch 函数的解析值是Response，它有一个.json() 方法，你忘了模拟它。

你忘了像return fetch(/.../)一样返回承诺。这会导致测试用例中的promise链不等待fetch promise完成，这就是为什么返回结果是undefined

例如

api.js:

const config = 
  apiUrl: 
    myFleetAPI: 'http://localhost:3000/api',
  ,
;
export async function getUserTest() 
  return fetch(config.apiUrl.myFleetAPI, 
    method: 'GET',
    headers: 
      Accept: 'application/json',
      'Content-Type': 'application/json',
      Authorization: 'Bearer ' + 'GcGs5OF5TQ50sbjXRXDDtG8APTSa0s',
    ,
  )
    .then((response) => 
      return response.json();
    )
    .catch((reject) => console.log(reject));

api.test.js:

import  getUserTest  from './api';

describe('68771600', () => 
  test('should pass', () => 
    const testData =  current_user: 'Rahul Raj', name: 'Lafarge' ;

    const response =  json: jest.fn().mockResolvedValueOnce(testData) ;
    global.fetch = jest.fn().mockResolvedValueOnce(response);

    return getUserTest().then((data) => 
      expect(data).toEqual(testData);
    );
  );
);

测试结果：

 PASS  examples/68771600/api.test.js (9.885 s)
  68771600
    ✓ should pass (3 ms)

----------|---------|----------|---------|---------|-------------------
File      | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s 
----------|---------|----------|---------|---------|-------------------
All files |      80 |      100 |   66.67 |      80 |                   
 api.js   |      80 |      100 |   66.67 |      80 | 18                
----------|---------|----------|---------|---------|-------------------
Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        10.794 s